vm: overhaul

VM infrastructure currently has several problems:
 - Config struct is complete mess with a superset of params for all VM types
 - verification of Config is mess spread across several places
 - there is no place where VM code could do global initialization
   like creating GCE connection, uploading GCE image to GCS,
   matching adb devices with consoles, etc
 - it hard to add private VM implementations
   such impl would need to add code to config package
   which would lead to constant merge conflicts
 - interface for VM implementation is mixed with interface for VM users
   this does not allow to provide best interface for both of them
 - there is no way to add common code for all VM implementations

This change solves these problems by:
 - splitting VM interface for users (vm package) and VM interface
   for VM implementations (vmimpl pacakge), this in turn allows
   to add common code
 - adding Pool concept that allows to do global initialization
   and config checking at the right time
 - decoupling manager config from VM-specific config
   each VM type now defines own config

Note: manager configs need to be changed after this change:
VM-specific parts are moved to own "vm" subobject.

Note: this change also drops "local" VM type.
Its story was long unclear and there is now syz-stress which solves the same problem.

1 files changed, 77 insertions, 0 deletions

diff --git a/vm/vmimpl/vmimpl.go b/vm/vmimpl/vmimpl.go
new file mode 100644
index 000000000..4c542429c
--- /dev/null
+++ b/vm/vmimpl/vmimpl.go
@@ -0,0 +1,77 @@
+// Copyright 2017 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+// Package vmimpl provides an abstract test machine (VM, physical machine, etc)
+// interface for the rest of the system. For convenience test machines are subsequently
+// collectively called VMs.
+// The package also provides various utility functions for VM implementations.
+package vmimpl
+
+import (
+	"errors"
+	"fmt"
+	"time"
+)
+
+// Pool represents a set of test machines (VMs, physical devices, etc) of particular type.
+type Pool interface {
+	// Count returns total number of VMs in the pool.
+	Count() int
+
+	// Create creates and boots a new VM instance.
+	Create(workdir string, index int) (Instance, error)
+}
+
+// Instance represents a single VM.
+type Instance interface {
+	// Copy copies a hostSrc file into VM and returns file name in VM.
+	Copy(hostSrc string) (string, error)
+
+	// Forward setups forwarding from within VM to host port port
+	// and returns address to use in VM.
+	Forward(port int) (string, error)
+
+	// Run runs cmd inside of the VM (think of ssh cmd).
+	// outc receives combined cmd and kernel console output.
+	// errc receives either command Wait return error or vmimpl.TimeoutErr.
+	// Command is terminated after timeout. Send on the stop chan can be used to terminate it earlier.
+	Run(timeout time.Duration, stop <-chan bool, command string) (outc <-chan []byte, errc <-chan error, err error)
+
+	// Close stops and destroys the VM.
+	Close()
+}
+
+// Env contains global constant parameters for a pool of VMs.
+type Env struct {
+	// Unique name
+	// Can be used for VM name collision resolution if several pools share global name space.
+	Name    string
+	Workdir string
+	Image   string
+	Debug   bool
+	Config  []byte // json-serialized VM-type-specific config
+}
+
+// Create creates a VM type that can be used to create individual VMs.
+func Create(typ string, env *Env) (Pool, error) {
+	ctor := ctors[typ]
+	if ctor == nil {
+		return nil, fmt.Errorf("unknown instance type '%v'", typ)
+	}
+	return ctor(env)
+}
+
+// Register registers a new VM type within the package.
+func Register(typ string, ctor ctorFunc) {
+	ctors[typ] = ctor
+}
+
+var (
+	// Close to interrupt all pending operations in all VMs.
+	Shutdown   = make(chan struct{})
+	TimeoutErr = errors.New("timeout")
+
+	ctors = make(map[string]ctorFunc)
+)
+
+type ctorFunc func(env *Env) (Pool, error)